Before a person can call himself a member of a religion, the person has to go through many things.
But a person can be saved, be born again and be declaring himself a Christian just by believing in fundamental doctrine.
Basic doctrine can be used to check whether a person is just a nominal Christian.

Salvation is by faith alone, or else it cannot be called gospel or good news.
It is free.
We just need to take a little time to get it.
We do not have to give anything or fulfill certain conditions to receive salvation, such as:
1) to get someone to pray with us. Salvation can be obtained via DIY.
2) to promise to Jesus Christ not to sin anymore.
3) to live like a monk, using own effort to resist from sinning.
Resistance from sinning will come automatically after salvation.
It is useless / futile to force ourselves to resist the sin before the salvation.
4) to give ourselves to Jesus Christ. How to do that anyway?
5) To attend church. Once a person is saved, that person will want to look for church to attend.
6) To get baptized.

Can God be bribed with good deeds to get salvation?
And how many good deeds should be done to purchase the salvation?
The salvation by faith is free anyway. Why make it difficult?
The sequence should be "salvation - natural good deed" instead of "deliberate good deed - salvation".
But that does not mean to deliberately go out to scout for some good deeds to do.
Just avoid doing the wrong things while living on usual daily life.
To make a person stop doing the wrong thing, just make sure the person gets the simple salvation.
Then let the Holy Spirit takes over (Romans 5:5, 2 Corinthians 5:17, Galatians 5:22, 2 Thessalonians 1:11).
Real faith will result in real resistance to sin.

Shield of the Trinity

The effect AFTER being saved (from the eternal damnation after death) and born again:
a) Resistance to sin increases.
b) Mental stress decreases due to a).
c) Believe that Bible is God's words so it is free of error.
d) Eager to interact with other Christians.
e) Accept to be baptized.
f) Never leave Christianity.

If a person claims that he becomes a Christian but he sins habitually or leaves Christianity later, he actually has no faith from the beginning.
Fruits of Holy Spirit cannot be seen on him.
Holy Spirit has never indwelt in him.
He has never been born again and saved.
The person who leaves Christianity may claim he was a devout Christian but he may not understand or believe the gospel.
In Christianity, there is no such thing as once believed but no more.
It is either belief or not.
It indeed takes time to know whether a person is a Christian or not because we are not God.
That is why baptism should not be performed yet if the person is known to be sinning habitually.

Nobody in the world who has not sinned.
Under human's standard, good guys sin only 10% of the time and bad guys sin 90% of the time.
According to God's standard, only 0% sin is acceptable.
Thus without salvation, good guys and bad guys will both go to hell.

Gospel preaching

Gospel is called good news because salvation can be obtained by just faith and cannot be lost.

Before sharing the gospel, ask permission from the person first.
Example: Are you interested to know about Christian gospel?
If the person says no, then move on because he has chosen to close himself from anything Christian for now.
Further attempt of sharing may drive him further away from the gospel in future.

Preach the gospel clearly only one time to one person.
If the person rejects it, move on.
Other Christians may preach to that person too after us.
A person does not have to preach seven times to one person himself.
It is better to have seven Christians preaching to that person one after another, one time each.
Of course, if the person is our direct family member, then we can preach as many times as we want.

If someone asks unreasonable question that may not build up his own faith but to bring further argument, then do not answer it.
It will waste his time.
Avoid talking something that others will gain nothing after listening such as
a) too much biblical knowledge / Bible verses.
b) shortcoming of other Christians.
c) shortcoming of various religions.

Christians should not invite people who are not Christians to go to church.
Christians should get them saved.
Once they are saved (and become Christians), they will automatically want to go to church that they choose themselves.
Churches just have to make sure they, including their websites, are up all the time and publicly accessible.

If a Christian attends church regularly, as long as the person's church is not a cult, it is pointless to invite the person to change church.

Do not abruptly declare a person as Christian after he claims to accept the gospel.
It may backfire.
It takes time to know whether he is Christian by seeing his fruits because we are not God.
A tree takes time to bear fruits.
It is irresponsible to declare something that is unsure.
Even a company has a probation period for new employee to get opinion established for the person.
The person himself can be sure he is saved if he has started to see moral improvement in him compared to last time.

Bible

God does not expect everyone to fully understand everything in the Bible.
Do not let the urge of understanding the Bible be the stumbling block for us to read His word.
Reading His word itself is already a blessing.
God used only word to create this world.

The Bible is inerrant but some parts are hard to understand for readers who do not have faith in God's justice.
Some parts can be taken literally while some parts cannot.
Orthodox theological interpretation is still needed.
Basically if an interpretation does not glorify God, it is wrong interpretation.
People who do not believe that God is just will interpret the Bible to despise God's justice.
Cults do not believe in fundamental Christian doctrines so their interpretation of one part of the Bible contradicts with another part of the Bible.
Such contradition can become a laughing stock that brings down the name of God.

The only book we can use along with the Bible is a dictionary.
If we write down the meaning beside the unfamiliar word, we do not even have to use the dictionary anymore next time.

When we encourage somebody to read the Bible, we have got to ensure he or she reads the "correct" Bible.
There are some so-called Bibles that have some obvious deviations.
These bible are automatically rejected by all non-cultic denominations.
I do not think God is happy with existence of many versions of Bible in same language.
We all, regardless of our denomination, should refer to one version of Bible.
I recommend King James Bible (KJV or AV) because it has been being used since year 1611.
I think that is the year the Dark Age ended and the development of English to an international language started.
A copy of it is available for download at the bottom of this article.

Old Testament (OT) laws are replaced by New Testament (NT).
Thus do not quote the OT to show something is a sin although OT may have the same thing as NT.
For example contract A (obsolete) clause 123 may be the same with contract B clause 321 but contract A should not be quoted because it is already obsolete as a whole.
Practical purpose behind certain OT laws may be good to use as knowledge on the personal basis but it is not mandatory, such as on what not to eat.
Colossians 2:14 Blotting out the handwriting of ordinances that was against us, which was contrary to us, and took it out of the way, nailing it to his cross;

Church services

Interact with church members.
Of course in the service we should talk more about God and His words, not gossip etc.
Even just say hi and walk away is better than nothing at all or else it kind of defeats the purpose of going to the service.
Do not either just learn to interact with God or just learn to interact with people.
These two aspects must be parallel.

People have the freedom to choose their own church.
We can provide them a list of cults to avoid and tell them how the church should be.
How the church should be in my opinion:
1) Services are not made compulsory (with gift or penalty).
2) Bringing newcomer is not made compulsory (with gift or penalty).
3) Baptism is given only if a person knows that he is already saved.
Salvation is by faith alone.
4) Members are not encouraged to leave family.
5) Members are not encouraged to socialize only with fellow members, further to date and marry only fellow members.
Christians should get along with anybody just like Jesus Christ did, but that does not mean following people to do impropriate things such as hanging out at a pub late night.
6) Members are not encouraged to read only materials published by the church.
7) Members are encouraged to exercise physically.
Weak body does not glorify God.
8) The church does not claim that it is the only true church or that a person can only become a Christian when baptized by that church.
9) Confessing sin or private thought to an individual is to be stopped.
10) Members are not pushed to shift to live near to the church.
Practically we should live near to our working place.
11) Only Bible verses should be read out and discussed in services, not any other Christian publication.
12) No names other than the ones in the Bible are to be mentioned frequently.
If a newcomer hears Spiderman a lot in the services, that person may misinterpret that Spiderman is as important as Jesus Christ.
13) One can leave the church (e.g. becoming a non-believer) without any problem.
Do not ask the church because all will definitely say yes although some in reality do not release its member easily.
14) Every week the church reminds all to read Bible at home.
Only churches that do not want Christian to be constituted with truth do not encourage Christians to read Bible themselves.
15) Gospel is preached merely to get people saved, not to increase people in the church.
16) The date of doomsday is not discussed.

The service should not have practices that may make newcomer uncomfortable:
1) I think passing offering bag or tray is good but having an idle non-transparent offering deposit box is better.
The box can be placed next to the exit so that the offering act by an individual is not that obvious because he or she just drops the offering in the box on the way out.
Envelope is not needed.
Banking into church's account can be a way too.
2) Male and female sittings are not separated.
There is no such teaching in the Bible.
3) There is no high decibel of sound (from yelling or music).
4) Anyone can talk (share or ask question).
The main preacher should not rush to finish a certain topic by shunning off people's participation.
For this to be achievable without microphone, the congregation should not be too big.
When the congregation is growing, then new place for service can be set up.
The new service place is chosen by member's vote.
5) Doubt about the church doctrine can be openly discussed without facing hostility.
6) There is no speaking that cannot be interpreted (1 Corinthians 14).
7) There is no chanting-like speaking.
For example even a single word like amen may be perceived as chanting if it is repeated habitually.
If some members want to say amen when hearing a preaching, they should be sure that they understand the preaching.
Only then it is a true amen, not a habitual amen.
Is it not a lie if we say amen to something that we do not understand?
Verbal repetition of word is risky as it may lead to mind control.
We should not even chant the name of Jesus Christ.
8) There is no candle in the service if possible.
What is the purpose of having candles in service?
It ain't no candlelight dinner or blackout.
9) The church is open to public that anybody can walk in (Luke 11:33).
10) If possible, avoid calling the service as "worship".
This may stop unbelievers from walking in because they think they will worship something that they do not believe in yet.
Plus we should worship God all the time, not only in the service.
11) People who do not give attention to sharing will not be scolded as long as they do not disturb the service.
12) Members should approach newcomers to give self introduction.

No denomination that men have created knows all the will of God through the Bible.
If we realize the errors of the denomination where we are in now, just bear with the errors.
We may try not follow the rest to practice the errors ourselves.
The most we can do is to write a book about what we understand and declare in the last page that it must NOT be used to create more division.
Any church should admit that their own church is not perfect.
Any church has some deviations from what the Bible really wants and it is just a matter of more or less and major or minor.
As long as there is no major deviation, then God will still bless the church.
When a church starts to say that it is a true church, then it falls into cult category.
Come on, if we are truly handsome, we do not have to say it.
Only if we are not a truly handsome person and we want to gain support that we always proclaim ourselves to be one.
Self-glorification about knowing God is dangerous.

Others

Nothing can fully resemble Trinity because Trinity is the one and only.
Explanation can only be done by analogy.
Trinity is quite analogous to sunlight.
Red spectrum is sunlight, orange spectrum is sunlight and so on, but yet there is only one sunlight.

Even other Christians practice something that God do not like as shown in the Bible, do not condemn them.
We ourselves just do what God want.
This does not only save us tiring argument, but also save us from the risk of becoming like fallen angel due to thought that we are more superior than other Christians.

Do not rationalize / whiten a sin.
People who commit a sin but according to conscience do not deny it is a sin is better than people who rationalize it.

We do not have to go around telling others that we are Christian unless people ask us.
Nevertheless, we can state our belief in our profile or resume.
I notice that the people who always say they are Christian usually do something religiously extreme.
They are also usually some cult members that need recognition from others.

Although God have given us some guidelines on what we should not eat, God will not be angry, if we eat unclean meat.
In other word, we are not bad guys if we eat unclean meat.
It is not a sin.
The only benefit of following the guidelines is we will have less physical illness.
Do not purposely speak to other brothers just tell them to avoid unclean meat because many things are not as important as salvation itself (see Col. 2:16).
Only tell the brothers that it is a personal choice to avoid unclean meat.
When the brothers ask why, tell them the ill-causing effect of the unclean meat such as pork.
Tell them too if we personally do not like the taste if that is the case.
Only when they understand the ill-causing effect, then proceed with asking them whether they know about Leviticus 11 and let them read it themselves.
Similarly God have allowed us to eat meat (Gen. 9:3) but if we choose to be vegetarian, that should be just personal preference and do not try to influence others to follow or accomodate us.
And we have to walk closely with God.
Note that now there is no longer vitamin B12 in vegetables because it has been eliminated by modern agricultural practice.
We can guess that the farming technique before The Great Flood was healthier.

Not only people know a friendly fat old folk in red suit more than Christ, Christ did not say that we should remember His birth.
However there is a strong reason to remember it: no birth, no Christ.

Other ways Satan tries to control humans are to
a) tempt humans into polluting the Earth.
When the Earth is not readily livable then life sustaining device will be manufactured to control humans.
All flora and fauna created by God are to maintain balanced ecosystem.
b) influence humans to be ignorant about natural health.
Then artificial health equipment and medical practice can be introduced to control humans.
Satan wants people to die as soon as possible to minimize the chance for them knowing the gospel.

If somebody tells us that he or she sees vision from God that we should / must do this and that, we have got to see if he or she has just banged the head on the wall or something.